I kind of find it hard to believe the majority of the actors would be in favor of rushing the plot just to be done with it. Nailing the landing is better for everyone. The showrunners are replaceable in my opinion. I mean, it is not like acting in Game of Thrones prevents you from doing other projects, many of them have been in other films or projects, major ones even. Just look at Peter Dinklage. However, like with the MCU, these actors get significantly more expensive as their careers progress and as with all large series, their demands become higher (which is their right). Offcourse, some actors probably really don't feel like doing it. But in terms of career progression, major Hollywood stars have been doing stage plays and shows (cable/streaming) inbetween high profile productions as well, so I don't buy being tethered to the biggest series of all time, with not all that much screentime, is detrimental to your career. And a longer season (10 instead of 6?), perhaps with some timeskips, could have been sufficient as well in my opinion.